Find the curve defined by the equation
\[r = 2.\](A) Line
(B) Circle
(C) Parabola
(D) Ellipse
(E) Hyperbola

Enter the letter of the correct option.
Every point on the graph has a distance of 2 from the origin, so the graph is a circle.

[asy]
unitsize(2 cm);

draw(Circle((0,0),1),red);
draw((-1.2,0)--(1.2,0));
draw((0,-1.2)--(0,1.2));

label("$r = 2$", (1.2,0.8), red);
[/asy]

The answer is $\boxed{\text{(B)}}.$